diff --git a/packages/provision-kit/src/install-source-download.test.ts b/packages/provision-kit/src/install-source-download.test.ts
index dbd6e4c742..119a18684a 100644
--- a/packages/provision-kit/src/install-source-download.test.ts
+++ b/packages/provision-kit/src/install-source-download.test.ts
@@ -5,6 +5,7 @@ import { Readable } from 'node:stream';
 import { test, vi } from 'vitest';
 import { mkdtempForTest } from './tmp-dir.fixtures.ts';
 import { downloadInstallSource } from './install-source-download.ts';
+import { isTrustedInstallSourceUrl } from './install-source.ts';
 import * as networkTransport from './install-source-network-transport.ts';
 
 test('download redirects revalidate destinations and strip sensitive cross-origin headers', async () => {
@@ -242,3 +243,17 @@ function response(
     close: async () => {},
   };
 }
+
+test('download and the trusted-source check refuse an unparsable source alike', async () => {
+  const source = '/abs/path/app.zip';
+  const expected = { code: 'INVALID_ARGS', message: 'Invalid source URL' };
+  await assert.rejects(
+    downloadInstallSource({
+      tempDir: '/unused',
+      url: source,
+      signal: new AbortController().signal,
+    }),
+    expected,
+  );
+  assert.throws(() => isTrustedInstallSourceUrl(source), expected);
+});
diff --git a/packages/provision-kit/src/install-source-download.ts b/packages/provision-kit/src/install-source-download.ts
index ac6bc6b362..9fd53df554 100644
--- a/packages/provision-kit/src/install-source-download.ts
+++ b/packages/provision-kit/src/install-source-download.ts
@@ -208,7 +208,7 @@ function parseSourceUrl(raw: string): URL {
   try {
     parsed = new URL(raw);
   } catch {
-    throw new AppError('INVALID_ARGS', 'Invalid source URL');
+    throw invalidSourceUrlError();
   }
 
   if (parsed.username || parsed.password) {
@@ -216,3 +216,7 @@ function parseSourceUrl(raw: string): URL {
   }
   return parsed;
 }
+
+export function invalidSourceUrlError(): AppError {
+  return new AppError('INVALID_ARGS', 'Invalid source URL');
+}
diff --git a/packages/provision-kit/src/install-source.ts b/packages/provision-kit/src/install-source.ts
index 1cbe44931c..53e2391727 100644
--- a/packages/provision-kit/src/install-source.ts
+++ b/packages/provision-kit/src/install-source.ts
@@ -12,7 +12,7 @@ import {
   noteInstallArtifactArchiveDepth,
 } from './install-artifact-archive-context.ts';
 import { approveDownloadSourceUrl } from './install-source-network.ts';
-import { downloadInstallSource } from './install-source-download.ts';
+import { downloadInstallSource, invalidSourceUrlError } from './install-source-download.ts';
 
 type MaterializeLocalSourceResult = {
   localPath: string;
@@ -158,7 +158,8 @@ export async function validateDownloadSourceUrl(parsedUrl: URL): Promise<void> {
  * whether a URL names a GitHub Actions or EAS artifact, which says nothing about who built it.
  */
 export function isTrustedInstallSourceUrl(sourceUrl: string | URL): boolean {
-  const parsed = sourceUrl instanceof URL ? sourceUrl : new URL(sourceUrl);
+  const parsed = sourceUrl instanceof URL ? sourceUrl : URL.parse(sourceUrl);
+  if (!parsed) throw invalidSourceUrlError();
   const hostname = parsed.hostname.toLowerCase();
   if (!hostname) return false;
   const pathname = parsed.pathname;
diff --git a/src/__tests__/cli-install-from-source.test.ts b/src/__tests__/cli-install-from-source.test.ts
new file mode 100644
index 0000000000..bc103e7649
--- /dev/null
+++ b/src/__tests__/cli-install-from-source.test.ts
@@ -0,0 +1,59 @@
+import assert from 'node:assert/strict';
+import { test } from 'vitest';
+import { AppError } from '@agent-device/kernel/errors';
+import type { AgentDeviceClient } from '../agent-device-client.ts';
+import { tryRunClientBackedCommand } from '../cli/commands/router.ts';
+
+const REACHED_CLIENT = new Error('reached the client');
+
+async function runInstallFromSource(source: string) {
+  const client = {
+    apps: {
+      installFromSource: async () => {
+        throw REACHED_CLIENT;
+      },
+    },
+  } as unknown as AgentDeviceClient;
+  return await tryRunClientBackedCommand({
+    command: 'install-from-source',
+    positionals: [source],
+    flags: { json: false, help: false, version: false },
+    client,
+  });
+}
+
+test('install-from-source refuses a local path with a typed error', async () => {
+  await assert.rejects(
+    () => runInstallFromSource('/abs/path/app.zip'),
+    (error) =>
+      error instanceof AppError &&
+      error.code === 'INVALID_ARGS' &&
+      error.message === 'install-from-source <url> must be an http(s) URL: /abs/path/app.zip' &&
+      String(error.details?.hint).includes('install <app> <path>'),
+  );
+});
+
+for (const source of [
+  'http://',
+  'https://',
+  'http://exa mple.com/app.zip',
+  'ftp://example.com/app.zip',
+  'example.com/app.zip',
+]) {
+  test(`install-from-source refuses ${JSON.stringify(source)} before any work`, async () => {
+    await assert.rejects(
+      () => runInstallFromSource(source),
+      (error) =>
+        error instanceof AppError &&
+        error.code === 'INVALID_ARGS' &&
+        String(error.details?.hint).includes('install <app> <path>'),
+    );
+  });
+}
+
+test('install-from-source passes an http(s) URL to the client', async () => {
+  await assert.rejects(
+    () => runInstallFromSource('HTTPS://example.com/app.zip'),
+    (error) => error === REACHED_CLIENT,
+  );
+});
diff --git a/src/__tests__/install-source.test.ts b/src/__tests__/install-source.test.ts
index 082ed328d1..467ff74683 100644
--- a/src/__tests__/install-source.test.ts
+++ b/src/__tests__/install-source.test.ts
@@ -24,6 +24,7 @@ import {
   withAppleToolProvider,
 } from '@agent-device/platform-apple/tool-provider';
 import { prepareIosInstallArtifact } from '@agent-device/platform-apple/install-artifact';
+import { AppError } from '@agent-device/kernel/errors';
 import { ANDROID_INSTALL_SOURCE_CONTRACT_EVIDENCE } from './install-source.coverage.ts';
 import { mkdtempForTest } from './test-utils/tmp-dir.ts';
 import * as networkTransport from '@agent-device/provision-kit/install-source-network-transport';
@@ -104,6 +105,13 @@ test('isTrustedInstallSourceUrl recognizes supported artifact services', () => {
     false,
   );
   assert.equal(isTrustedInstallSourceUrl('https://expo.dev/pricing'), false);
+  assert.throws(
+    () => isTrustedInstallSourceUrl('/abs/path/app.zip'),
+    (error: unknown) =>
+      error instanceof AppError &&
+      error.code === 'INVALID_ARGS' &&
+      error.message === 'Invalid source URL',
+  );
 });
 
 test.sequential('materializeInstallablePath extracts zip archives without ditto', async () => {
diff --git a/src/commands/management/install.ts b/src/commands/management/install.ts
index 7155d10e09..6258fa58e7 100644
--- a/src/commands/management/install.ts
+++ b/src/commands/management/install.ts
@@ -204,6 +204,11 @@ function resolveInstallSource(positionals: string[], flags: CliFlags) {
   }
   if (githubArtifactSource) return githubArtifactSource;
   if (configuredSource) return configuredSource;
+  if (!isHttpUrl(url!)) {
+    throw new AppError('INVALID_ARGS', `install-from-source <url> must be an http(s) URL: ${url}`, {
+      hint: 'Install a local build with install <app> <path>.',
+    });
+  }
   return {
     kind: 'url' as const,
     url: url!,
@@ -211,6 +216,11 @@ function resolveInstallSource(positionals: string[], flags: CliFlags) {
   };
 }
 
+function isHttpUrl(value: string): boolean {
+  const protocol = URL.parse(value)?.protocol;
+  return protocol === 'http:' || protocol === 'https:';
+}
+
 function parseInstallSourceHeaders(
   headerFlags: CliFlags['header'],
 ): Record<string, string> | undefined {